AI Article Synopsis

  • Advances in microscopy, particularly single-molecule super-resolution microscopy, are improving our ability to visualize and measure molecular interactions in living cells.
  • HP1 proteins are key players in gene regulation by binding to H3K9 methylated histones, forming complexes that can silence gene expression.
  • Our study in fission yeast reveals that H3K9me not only helps HP1 proteins form specific complexes within the nucleus but also limits their ability to bind to other complexes outside of chromatin, indicating a more active role for H3K9me in these interactions.

Article Abstract

Visualizing and measuring molecular-scale interactions in living cells represents a major challenge, but recent advances in microscopy are bringing us closer to achieving this goal. Single-molecule super-resolution microscopy enables high-resolution and sensitive imaging of the positions and movement of molecules in living cells. HP1 proteins are important regulators of gene expression because they selectively bind and recognize H3K9 methylated (H3K9me) histones to form heterochromatin-associated protein complexes that silence gene expression. Here, we extended live-cell single-molecule tracking studies in fission yeast to determine how HP1 proteins interact with their binding partners in the nucleus. We measured how genetic perturbations that affect H3K9me alter the diffusive properties of HP1 proteins and each of their binding partners based on which we inferred their most likely interaction sites. Our results indicate that H3K9me promotes specific complex formation between HP1 proteins and their interactors in a spatially restricted manner, while attenuating their ability to form off-chromatin complexes. As opposed to being an inert platform or scaffold to direct HP1 binding, our studies propose a novel function for H3K9me as an active participant in enhancing HP1-associated complex formation in living cells.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10028927PMC
http://dx.doi.org/10.1101/2023.03.08.531771DOI Listing

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